Circuit breaker



A Oct. 26, 1943. H. G. BAXTER CIRCUIT BREAKER Filed Jan. 28, 1942 Insubria INVENTOR Ham/a7 dxfe".

WITNESSES:

Patented Oct. ze, 194sV CIRCUIT BREAKER Harold G. Baxter, Wilkinsburg, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application January 28, 1942, Serial No. 428,484

(Cl. o-116) 12 Claims.

This invention relates to circuit breakers and, more particularly, to circuit breakers of the type which are opened and closed manually and which are opened automatically in response to predetermined circuit conditions.

One object of the invention is to provide an improved manually and automatically operable circuit breaker that is characterized by the absence of any latching means.

Another object of the invention is to provide an improved trip free circuit breaker wherein a thermal vtrip element functions to operate a toggle to cause opening of the breaker irrespective of the position of the manual operating member.

Another object of the invention is to provide an improved trip free circuit breaker wherein a switch member is movable to open' and close the circuit through the agency of a toggle mechanism and in which a bimetal element, mounted on the switch arm for movement therewith, is operable to positively operate the toggle to initiate automatic opening operation of the switch member.

Another object of the invention is to provide an improved circuit breaker having an operating mechanism including a manual operating member, an overcenter spring and a. toggle operable to move a switch member to open and closed positions, and a bimetal element mounted on the switch member for movement therewith operable to positively move the toggle in a direction to initiate an opening movement by the switch member, the manual operating member having a member pivotally mounted thereon for movement therewith which is operable upon closing movement of said manual member to positively initiate movement of the toggle in a direction to 'close the switch member.

Another object of the invention is the provision of an improved manually and automatically operable trip free circuit breaker which does not require any manual resetting operation after an automatic openingoperation.

Another object of the invention is to provide a circuit breaker embodying an improved operating mechanism which is simple, efcient and reliable in operation, and which is inexpensive to manufacture.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims; the invention itself, however, bothas to structure and operation, together with additional objects and advantages thereof, will be best understood from the following description of one embodiment lil thereof when read in conjunction with the accompanying drawing in which:

Figure l is a vertical sectional view through a circuit breaker embodying the principles of the invention, the section being taken substantially on line I--I of Fig. 2;

Fig. 2 is a transverse sectional View through the circuit breaker taken substantially on line II-II of Fig. l;

Fig. 3 is a vertical sectional view similar to Fig. 1, but showing the breaker mechanism manually operated to open contact position; and

Fig. 4 is an enlarged perspective view of the resetting member.

Referring to Fig. 1, the circuit breaker comprises in general a tw-o part housing including an open sided housing member of molded insulating material, and a cooperating side cover plate I3 also of molded insulating material removably secured to the housing member II by means of bolts I4, a stationary contact I5, a movable contact I1, a thermally responsive trip member I9 comprising a strip of bimetallic material, an operating mechanism indicated generally at 2| including an operating lever 23, and an arc extinguisher 24. Terminals 25 and 21 are provided for connecting the breaker in an electrical circuit.

The stationary contact I5 is mounted on the inner end cf the terminal 25 and cooperates with the movable contact Il, which is mounted on the free end of a resilient contact arm 29 secured to a pivoted switch member 3| of conducting material. The switch member 3| is pivotally supported on a pivot pin 33 mounted in the side wall of the housing member II, and in an opening in the cover plate I3. One leg of an L-shaped bimetal element I9 is secured by means of a screw 3l to the free end of the switch member 3|, and the other leg of the bimetal element extends toward the left (Fig. 1) to a point slightly beyond the pivot point ofthe switch member. A iiexible conductor 39 connects the free end of the bimetal element I9 to the inner end of the terminal 2l, completing the electrical circuit for the breaker which extends from the terminal 25 through the contacts I5 and Il, the resilient Contact arm 29, the switch member 3|, the bimetallic trip member I9, and the flexible conductor 39 to the terminal 21.

The operating lever 23 comprises a U-shaped lever, the two legs of which are pivotally mounted at their inner ends on a pivot pin 4I supported in the housing member I I and in the cover plate I3. At its outer end, the operating lever 23 has secured thereto, by suitable means, an arcuate insulating shield 43 from which a manual operating handle 45, also of insulating material, projects through an opening 41 in the outer wall 36 of the closure.

The operating mechanism 2| includes a toggle comprising a pair of toggle links 49 one disposed on each side of the switch member 3| and pivotally connected thereto by'means of a pivot pin 5|, and a pair of toggle links 53, which are pivotally supported at their outer ends on pins 55 one of which is supported in and projects inwardly from the housing member the other pin 55 being supported in the cover plate I3. The toggle links 49 and 53 are pivotally connected by a knee pivot pin 51, and an overcenter spring 59, having one end hooked over the knee pin 51 and the other end hooked through an opening in a projection 6|y integral with the operating lever 23, at all times exerts a tension force between the knee of the toggle and the outer end of the operating lever.

The toggle links 53 are L-shaped and each is provided with an arm 63 projecting toward the left (Fig. 1) from the knee of the toggle. The arms 63 are rigidly connected at their free .ends by a cross-member 65, which has an extension 61 in which is mounted an adjusting screw 69 having an insulating button 1| on its end with which the free end of the bimetal element |9 is adapted to cooperate to trip the breaker.

One leg of the U-shaped operating lever 23 has an ear 13. formed at right angles thereto and on which a member is pivotally mounted for transverse movement by means of a pivot pin 11. The member 15 s biased to a normal position parallel to the wall of the housing by a spring 19 secured by means of a projecting stud 8| to the leg of the operating lever 23 which carries the member 15. The stud 8| extends across the plane of one of the toggle links 53. The purpose of the member 15 will be described later.

With the parts in the position shown inv Fig. 1 the overcenter spring 59 biases the knee of the toggle 49-53 overcenter to the rightv of a line drawn through the center of the pins 5| and 5,5 and in this position the toggle maintains the contact I1v in engagement with contact |5. The overcenter movement of the toggle is limited by a stop member 83 projecting from the toggle link 49 and which engages the switch member 3l. I n this position, contact pressure is provided by the resilient contact arm 29.

Upon the occurrence of. an overload current in the circuit of the breaker, the bimetal element |.9 is heated by the excessive current ilowing therethrough, and when heated a predetermined amount, it ilexes in a direction away from the switch member 3 I. After iiexing a predetermined amount, the free end of the bimetal element engages the insulating end 1| of the screw 69 and rocks the L-shaped toggle links 5,3 clockwise (Fig. 1) about their pivot pins 55. Thlsoperates the toggle 49-53 over center in a.. direction to cause its collapse. During this movement. the line of action of the spring 59 passes over center to the left (Fig. 1)'of the line. 571-55., whereupon the spring exerts a force on theknee of the toggle in a direction to. complete collapse of the toggle. As the toggle 4.9-53 collapses, the switch member 3| is moved in a counterclockwise direction about its pivot 33, opening the contacts with a snap action. The clockwise or opening movement of the toggle links 53 Ais limited by one of the arms 63-striking a limit stopA 81 pro.- jecting inwardly from the side wall of thehous.-

ing A coil spring 85, having one end disposed against the base of the housing Il and the other end tensioned against the contact arm 29, biases the switch member 3| and the contact arm in the opening direction and assists the spring 59 in opening the contacts.

During the movement of the toggle 99-53 to collapsed position, the line of action of the spring 59`Ir`iovesover center vtothe left (Fig. 1) of a line drawn through the center of the pivot pin 4| for the operating lever 23 and the point of anchorage of the spring 59 to the projection 6|. As soon as the spring 59 passes to the left of the centerline 4|6|, it moves the operating lever 23 counterclolckwlseto its off position in which it appears irl Fig. 3, the counterclockwise movement of the operating lever 23 being limited by engagement with the pivot pins 55 for the toggle links 53. The mechanism is now ready to be closed. `It will be noted from the above that the mechanism does not requireV any manual resetting operation after. the breakerv has been tripped.

The switch member 3l is rotated in a clock wise or closing direction to close. the contests. bl manual movement of the operating. lever 2.34 from its Fig. 3 position in a clockwise direction toward its on position. During this movement of the operating lever 23, the upper corner 9|,` of the, previously mentioned memberV 15 mounted ther-mn engages a projection $9 on one of the arms 63 and starts the toggle. iii-.5.1i towardits` over center or in toggle position. Continued clockwise movement of; theI operating lever 23 after en gagement oi the member. 1.6 with the` projection Il causes the line of action of the spring 59` toA pass over center to the right of the line 513-55, where,- upon the toesio 49,-.-.53 moves over center to. its

,Eigf 1 position, closing the. contacts with 8. snel) action.-

'Ifhe contacts are opened manually by moving the hoodie 45 counter-clockwise. during whihL liliveinoni` the stud; {il} which, sfs previously stated, extends across the path of movement o1 the toggle link 53, engages said; link and positivelyv starts the toSg1e49-53 in a direction to Coils@ its. ooiispso As soonl os the. line. of action of; the` springv 53A moves over center` to theV left o! the 11.11, ile-.55', the spring. Causes collapse. ortho toggle and opening of thsoontaots withy a snee action,- lhs Contests are closed; in4 the previously (iosofibefiv mennen The circuit ivrosisorl is trip-free. of the handle: that is. if. the. contacts shouldt be closed. easiest en, overloadl in. the Circuity .the bimetaielement I will be hesiod; by. the excessive ciment. am vili-oo hosted s'. stedotsrmised amount. wiii, move the, iossl's 45t-5.1i. over center is. opening. dires. tion. Whenthe bimetal, has movedthe toggle iiiloushdoodseritor in opsn-ir1s'V disotioo. the lino of, sesos. of the serios 5.9 is4 sich ss. to complete the boilers@ of the vessie one. cause. opening o; the contests. @vos tl'iovsh4 the hoodie isjhelo. in

th on Pos-.iiioo- 1.11 this-.event 'whsntoetoslls 491-53. collapses. and; the tosslflinlt is moves. to the position, is. Whioiiit appears. iol Eisit itwiii sorry; tbsoroieotioo 8.9 on, the arm. se to sub. Siontisiiv the position indicated ai;- a in(f the dotted line` in Fig. 1. In order mi permit' am projection 8.9. tosass. the. member. 1.5. when. the handieis held in. the onit position. said-member has a, portion 99, of. reduced thickness. Ii: the handleisheld, inthe onpositlon during open. inc of. the. contacts. in. response been overleeft the. operating. 1ever 23.- ono. consequently. the member. 15:;wi11, remain` in, their. k positions whilethe toggle 49-53, the switch member 3l and the c'ontact arm assume their Fig. 3 positions. With the breaker in this condition, it is necessary, in order to close the contacts, to first allow the operating lever to move to the 01T position. During this movement, a beveled face 9| of the member 15 (Fig. 4) Wipes by the projection 89, rotating the member slightly clockwise (Fig. 2) until it clears projection. The spring 19 then restores the member 'l5 to its normal position, wherein a face 93 is in position to engage the projection 89 and start the toggle 49-53 over center in a direction to close the contacts when the handle is rotated to its on position. Y

The arc extinguisher 24 may be of any suitable type, preferablylof the type comprising a stack of slotted plates of magnetic-material wherein the arc drawn by rupture of the current is broken up into a series of short arcs which are quickly cooled and extinguished in a manner well known in the art.

From the foregoing description, it can b-e seen that I have provided a simple and inexpensive trip free circuit breaker having relatively few parts and no latching mechanism. The bimetal element has to overcome only the force necessary to move the toggle through dead center to trip the breaker, and the bimetal is then free to continue its flexing movement while heated without any opposition which might tend to give it a set.

Having described the invention in accordance with the patent statutes, it is to be understood that various changes and modifications may be made in the structural details disclosed without departing from some of the essential features of the invention. It is, therefore, desired that the language of the appended claims be given as reasonably broad interpretation as the prior art permits.

I claim as my invention:

1. A circuit'breaker comprising a switch member movable to open and closed positions, operating means for`moving said switch member to open and to closed position with a snap action, said operating means including an operating member'movable to open and closed positions, a toggle having one end pivoted to a xed sup-port and theother end pivotally connected to the switch member, an overcenter spring connecting the operating member to the knee of the toggle, and current-responsive means mounted on and movable with the switch member and operable in response to predetermined conditions to engage a portion of the toggle and move said toggle over center to cause opening movement of said switch member.

2. A circuit breaker comprising a switch member movable to open and to closed position, operating mechanism for moving said switch member to open and to closed position including an operating handle movable to open and closed positions, a toggle having one end pivoted to a iixed support and the other end pivotally connected to said switch member, an overcenter spring connecting the knee of said toggle to the operating handle, and a bimetal element mounted on said switch member for movement therewith, said bimetal being operable when heated a predetermined amount to flex in a direction to engage a portion of said toggle and move said toggle over center in a direction to cause opening movement of the switch member.

3. A circuit breaker comprising a switch member movable to an open and a closed position, operating means for moving said switch member to open and to closed position with a snap action, said operating means including an operating handle movable to an open and to a closed position, a toggle pivoted at one end to a fixed support and having a pivoted connection with said switch member at the other end for restraining the switch member in closed position, an overcenter spring connecting the knee of the toggle to the operating handle, an a thermally-responsive means mounted on said switch member and operable in response to predetermined conditions to engage a portion of the toggle and move said toggle over center in a direction to cause movement of the switch member to open position irrespective of the position of the operating handle.

4. A circuit breaker comprising a movable switch member, operating means for moving said switch member to an open position and ,to a closed position, said operating means including an operating handle movable to an open and to a closed position, a toggle having one end pivoted to a xed support and the other end pivotally connected to the switch member, an overcenter spring connecting the knee of said toggle to the operating handle, and a bimetal element mounted on said switch member for movement therewith, said bimetal element being heated in response to the current of the circuit and operable when heated a predetermined amount to ilex in a direction to engage the toggle and move said toggle over center in a direction to cause movement of the switch member to open position irrespective of the position of the operating handle.

5. A circuit breaker comprising a pivoted switch member movable to open and to closed position, operating means for said switch member including an operating handle movable to open and closed positions, a toggle having one end pivoted to a iixed support and the other end pivoted to said switch member, an overcenter spring connecting the knee of said toggle to the operating handle, a current responsive element mounted on said switch member for movement therewith, said current responsive element being operable to engage a part of the toggle and move said toggle over center in a direction to cause opening movement of the switch member, and means on the operating handle for engaging the toggle when said handle is moved to closed position to initiate movement of the toggle over center in a direction to cause closing movement of the switch member.

6. A circuit breaker comprising a switch member movable to open and closed positions, operating means for said switch member including an operating handle movable to open and closed positions, a toggle operable to cause movement of said switch member to open and closed positions, an overcenter spring connecting the knee of the toggle to the operating handle, a bimetal element mounted on the switch arm for movement therewith, said bimetal element being operable when heated a predetermined amount to positively move the toggle over center in a direction to cause opening movement of said switch member, and a member movably supported on the operating handle and engageable with the toggle when said handle is moved toward closed position to positively initiate movement of said toggle in a direction t0 cause closing movement of said switch member.

7;. A circuit breaker comprising aswitch membermovable to open and' closed positions, operating mechanismfor said switch member including an operatingy handle movable to open and closed positions and a toggle operable to cause opening; and closing movements of said' switch member, a. bimetal' element mounted onV the switch member for movement therewith, said bimetal. element being operable when heated a predetermined amount to positively operate the toggle in a direction to cause opening movement of the switch member, a member movably. mounted. on the operating handle for movement therewith, said member being operable upon movement of said handle to closed` position to positively initiate movement ot the toggle in. a direction to cause closing movement of said switch member, said.- bimetal element being operable to initiate operation of the toggle to cause opening. movement of the switch memberirrespective of the position of the handle.

81.v A circuit breakercomprising a. switch. member movable to open andV closed positions, oper.- ating. mechanism-for. said switch member includ.- ing anoperating levermovable to open and' closed positions and a toggle operable to cause movement of saidA switch member to open and. closed positions, an overcenter spring connecting. the knee of the toggle to the operating lever, a bi.- metal element operable when heated a predeterminedv amount. to positively operate the toggle in a direction. to cause opening.. movement of the switch arm, a` member movably mounted on the operating lever for movement therewith in openingy and closing directions. and for movement in another direction atan angle to its movement in opening and closing directions, said. member being operable. to engage the toggle whenthe Operating lever is moved toward closed position for initiating movement of, said togglein a direction to cause closing movement of the switch member, and said member being movablezin. said other direction topermit said member. to pass the` toggle when the operating lever. is. moved tov open position following an operation. of." the toggle by the bimetalelement.

9; A circuit breaker comprising a switch member movable to an-open and to aclosedposition, operating meansior moving said switchmember to open and-to closedzposition with a snap` action, said operating means including an operating handle movable to anopen and to a closed position, a-` toggle pivoted at` one end to a iixed-y support and having a. pivoted connection with theswitch member at the; other endfor restraining said switch member in .closed position, an overcenter spring connecting the knee of. the toggle tothe operating handletand current responsive means operable in response to predetermined conditions toengage a portion ofthe toggle and move` Said toggleover center in a direction to cause-.movement of the switch. member to Open position, said, handle being automatically moved,V toppen position by the overcenter springupcn autom-atie opening movement of the switchl member and said mechanism being; thenoperable tomove the switchl member to closed position without requiring any manual resetting operation.`

10. A circuit breaker comprising a switch member movable to open and closed positions, operatingt mechanism for said4 switch member including an operating lever movable to open and closed positions and aA toggle operable to` cause movement of said switeh member to open and closed positions, a bimeml element operable when heatedV a predetermined amount to positively operate the toggle in a direction to cause opening movement of -the switch.y arm, a member movably mounted on the operating lever for movement therewith in opening and. closing directions and for movement in another direction at an angle to its movement inl opening and closing directions, said member being operable to engage the toggle when the-operating lever is moved toward closed' position for initiating movement of said toggle in a direction to cause closing movement ofthe switch member, and said` member. being movable in said other direction. to permit said member to pass the toggle when the operating lever ismoved to open position following an operation of the toggle by the bimetal element.

11. A circuit breaker comprising a. pivoted switch member movable to open and to closed position, operating means for said switch member including an operating handle movable to open and closed positions, a toggle having one end pivoted to a iixed support and the other and pivoted to said switch member, a current responsive element, said currentresponsive element being operable to move said4 toggle over center in a direction tol cause opening movement of the switch member, and means on the operating handle for engaging the toggle4 when said handle is moved to closed position toinitiatemovement of the toggle over center-in a direction to cause closing,r movement of the switch member.

12. A circuit breaker comprising aY pivoted switch member movable to open and to closed position, operating means for said switch member including an operating handle movable to open and closed positions, al toggle having one end pivoted to a fixedY support and the other end pivoted to saidvswitch member, a current responsive elemenasaidcurrent responsive element being operable to move said toggle over center in a direction to cause opening movement ofthe switch member, andmeans on the operating handle for engaging the toggle when said handle is moved to closed position to initiate movement of the toggle overl center in a direction to cause closing movement of the switch member, said means on the operating handle disengaging the toggle when` in closed position andy permitting. said toggle to move the switch member to open position upon operationof the current responsive elementjeven though the operating handle is held in closed position.

HAROLD G. BAXTER. 

